JP-2009-57926A (US-2009/0056676A1) describes that a variation in fuel pressure due to a fuel injection through a fuel-injector is detected, and an actual fuel-injection-start timing and an actual fuel injection quantity are detected based on the detected fuel pressure waveform. For example, the actual fuel-injection-start timing is detected based on a fuel-pressure-drop-start point appearing on the fuel pressure waveform. The actual fuel injection quantity is detected based on the fuel-pressure-drop quantity. As above, if the actual fuel injection condition is detected, the fuel injection condition can be accurately controlled based on the detected fuel injection condition.
However, a correlation between the fuel-pressure-drop-start point and the actual fuel-injection-start timing and a correlation between the fuel-pressure-drop quantity and the actual fuel injection quantity are specific values in each fuel-injector. In JP-2009-57926A, such specific values (characteristic data) are previously experimentally obtained. These obtained characteristic data are stored in a memory provided to the fuel-injector. This memory provided to the fuel-injector will be referred to as an INJ-memory hereinafter. Then, before shipping the internal combustion engine, the characteristic data stored in the INJ-memory are transferred to a memory provided to an ECU. This memory provided to the ECU is referred to as an ECU-memory hereinafter. After the internal combustion engine is shipped into the market, an operation of the fuel-injector is controlled based on the characteristic data stored in the ECU-memory.
When the fuel-injector is replaced by new one after shipping the internal combustion engine, it is necessary that characteristic data of the new fuel-injector are transferred to the ECU to be stored in the ECU-memory (controller-memory means). However, if the fuel-injector is replaced by new one without changing the characteristic date stored in the ECU-memory into new data of the new fuel-injector, the new fuel-injector is operated based on the old characteristic data. Thus, the fuel injection condition can not be controlled with high accuracy.